Here is my proposal to FIDE for official GM titles:
GM–the base level with qualifications as presently set. Super Grandmaster–a fluctuating title for GMs rated between 2700 and 2799 Super Duper Grandmaster–a fluctuating title for GMs rated 2800 to 2899 Wizard Grandmaster–a fluctuating title for GMs rated 2900 to 2999 Supreme Wizard Grandmaster–a fluctuating title for GMs rated >3000
Wizard GM will end up getting abbreviated WGM, which conflicts with the Woman GM title. However, you could use another term for wizard and have an Adept GM.